A. Field of the Invention
This invention relates generally to the field of key and pivot spring assemblies for musical instrument keyboards.
B. Background Art
Keyboards for electronic musical instruments are well known in which flat springs have been used as the key mounting and biasing elements. In some cases, such as in U.S. Pat. Nos. 3,110,211; 3,616,722 and 3,738,216 individual vertical flat springs or groups of vertical springs formed in comb arrangements have been attached to the keys and/or keyboard chassis by rivets, screws, spotwelds or similar separate fastening devices. The use of these fastening devices has left much to be desired as it has caused problems in the preservation of tolerances. Specifically fastening operations such as punching, riveting, bending, etc. cannot readily be controlled which results in variations from assembly to assembly. Thus, upon installation, each assembly must be adjusted to provide proper clearance of key to switch. In addition, in many cases, fine adjustments have been required after installation all with predictably high labor costs. These methods of fastening have also complicated maintenance or repair procedures--sometimes necessitating removal of an entire section of keyboard to replace or adjust one key or spring.
U.S. Pat. No. 4,129,057 shows a method of employing a flat spring without rivets or screws. However, like most other flat spring arrangements of the prior art, the spring was horizontally disposed (i.e. substantially parallel to the major longitudinal axis of the key). Unfortunately, this disposition does not lend itself readily to resistance to rotational movement about the longitudinal axis of the key.